What does bluebird have to do with this? https://bluemail.me/ The dialog is telling you either authentication failed (unlikely) unless it has times out through some interference in the connection like antivirus scanning or you have consumed all of the 15 possible concurrent connections the google IMAP server allows. This is easily done if you are using an apple mail product. They routinely consume all available connections. Thunderbird will use up to 5 if they are available and as the dialog says you can change this figure in account settings at Server settings > Advanced